The following mod works exactly as described for the Icom IC-P7A (see mod for the IC-E7)

NOTE: The sticker is a very small (1cm) one and in the P7 the pads are shorted with a SMT diode. With a steady hand, a jewlers loupe, and some really small tweezers, you can pluck the diodes off lohoneyions 3 and 4 (as noted below.)
As per EB4EQA:

TX bands configuration via 4 solder pads in the PCB, behind a square sticker lohoneyed under the battery, on the top-left corner.

I've number the pads as seen while looking to the back of the transceiver, with no battery and the PTT looking to your right.